Expansion Board Replacement

This guide covers replacing the expansion board (Duet 3 EXP3HC) on the Vision Miner 22IDEX V3 and V4 - both versions use the same board and the same procedure. The expansion board drives the three Z motors, the bed and chamber heaters, the Z-probe, the chamber LEDs, and the chamber airflow fan, so a dead board takes all of these down at once. Before replacing it, work through the confirmation steps below - a board that shows no signs of life is rare, and in most cases the problem is elsewhere. For the main controller board, see the Main Board Replacement guide.

Tools and Materials

• Expansion Board
• PH2 Phillips screwdriver (for the 24V power terminal screws)
• 2 mm hex key (for the board mounting screws)
• Phone or camera (to photograph the wiring before disconnecting)

Confirming the Board Is Dead

The expansion board sits in the electronics bay below the mainboard. Both boards have power indicator LEDs - blue (24V), amber (12V), red (5V), green (3.3V) - and a DIAG status LED. On the expansion board the DIAG LED sits between the two CAN-FD connectors; on the mainboard it is next to the microSD slot. In normal operation both DIAG LEDs blink in sync, one second on, one second off. See Unresponsive Printer for the full LED reference.

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Work through these checks in order:

1. Compare the DIAG LEDs. If the power LEDs on the expansion board are lit but its DIAG LED does not blink at all while the mainboard's DIAG blinks steadily, the board is not booting.
2. Query the board over CAN. In the Web Interface console, send M122 B1. A dead board answers CAN response timeout: board 1. (Plain M122 should still return mainboard diagnostics normally.)

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3. Press the reset button. The small reset button is in the upper-right corner of the expansion board, facing the small optocoupler Z-probe board. Press it briefly, then try pressing and holding it for 3-5 seconds. Watch the DIAG LED for any reaction.

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4. Photograph the connections. A short circuit in a connected peripheral (a pinched sensor wire, a faulty fan or heater) can prevent the board from booting. Power the printer off and unplug the power cord. Take a clear photo showing where every cable is connected so you can reconnect them correctly later.

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5. Disconnect the peripherals. Unplug every peripheral connector and the CAN cable from the expansion board. Leave the 24V power input connected.

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6. Power the board with only 24V connected and check the DIAG LED. Make sure no peripheral or CAN cables remain connected. Plug in the printer and power it on. Watch whether the DIAG LED begins blinking.
   • DIAG stays completely dark - the board itself is dead. Replace it using the procedure below.
   • DIAG comes back to life - the board is fine, and one of the disconnected peripherals has a short. Power off and reconnect them one at a time, powering on after each, until you find the one that kills the board, then contact our support team.

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Removing the Old Board

1. Power off. Turn the printer off and unplug the power cord.
2. Keep the wiring photo available. Use the reference photo taken during the bare-board test when reconnecting the cables. If that test was skipped, take a clear photo of all connections before disconnecting anything. The Wiring Schematic (V4, V3) is the backup reference.
3. Disconnect the peripherals. If they are still connected, unplug all peripheral connectors and the CAN cable. If you performed the bare-board test, leave them disconnected.
4. Disconnect the power. Make sure the printer is unplugged. Unscrew the two screws securing the 24V power cables and free the cables.

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5. Remove the board. Unscrew the four screws holding the board on its standoffs with the 2 mm hex key and take the board out.

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Installing the New Board

1. Check the CAN address switches. Before mounting, make sure the CAN ADDR DIP switches on the new board match the old one: switch 1 up, the other three down (address 1). Do not change them afterwards.

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2. Set the power jumpers. Below the terminals where the 24V power line connects, there are two 3-pin contacts in one line, each with a 2-pin jumper on it. Move both jumpers to the far left position so each bridges the left-most and center pins when you are facing the board directly.

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3. Mount the board. Seat the new board on the four standoffs and fasten it with the four screws using the 2 mm hex key.
4. Connect the power. Attach the 24V power cables with the two terminal screws.
5. Reconnect the peripherals. Plug every connector back into its socket using the reference photo, and reconnect the CAN cable. Double-check against the Wiring Schematic (V4, V3).

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Verification

1. Plug the printer in and power it on. The expansion board's DIAG LED should start blinking in sync with the mainboard's - one second on, one second off. The chamber lighting coming on is another quick sign the board is alive, since the LEDs are driven by it.
2. In the console, send M122 B1 - the board should now return a full diagnostics report instead of a timeout. Send M115 B1 to check its firmware version.

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3. If the firmware versions do not match the mainboard, update the expansion board: type M997 B1 into the command line at the top of the screen and press Enter - the board pulls the correct firmware from the SD card. See SD Card & Firmware Recovery if anything goes wrong.

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FAQ

Support

If you could not find an answer here, reach out to our support team.